In many cities the utilities are located beneath the surface of the earth, usually beneath the surface of the streets. These utilities are usually placed in tunnels or conduits. In the older cities, such as New York City, these utilities have been located in these tunnels or conduits for many years/decades. Over time, the conduits which carry these utilities wear out and break. For example, water main breaks are a well known example of a utility conduit failing. Another serious problem is the failure of electrical transmission lines in conduits and tunnels. These failures usually result in fires which must be quickly extinguished to prevent further damage.
While it is desirable to replace very old utilities in conduits and tunnels, it is not always practical. Recently, a new tunnel for the supply of water was built under New York City. This was a tremendous project which took many years to complete and was very expensive. The replacement of the electrical transmission lines under the streets of New York City should also occur. However, due to financial restraints and other limitations, these transmission lines have not been replaced. Thus, these old electrical transmission lines break down or fail which results in electrical fires. These fires are commonly seen as smoke coming from manhole covers in the streets and sidewalks of a city. It has been estimated by Consolidated Edison that there are approximately 40 electrical fires per day in New York City.
The cost of repairing and replacing the electrical transmission lines damaged by these fires is approximately $100,000.00 per linear foot of transmission line. Therefore, it is imperative that these fires be extinguished as quickly as possible. Normally, when there is a fire, the firefighters locate the fire and call the utility to cut off the electrical power to that section of the electrical transmission line so that the fire can be extinguished with water. Because of the large voltage and current sent through these transmission lines, the application of water to these lines without the power being turned off would result in the instant electrocution of the firefighter. Accordingly, the firefighters wait until there is no doubt that all the electrical power has been turned off in the transmission lines they are about to extinguish. This, of course, results in the fire burning for an unnecessary extra amount of time and having the utility incur an unnecessary financial expense.
Once it has been established that the electrical power has been turned off, the firefighters enter the underground tunnel or conduit through a manhole and apply large amounts of water onto the electrical transmission lines which are on fire and/or smoldering until they determine that the fire has been completely extinguished and will not flare-up or restart. This large amount of water usually results in the destruction of good electrical transmission lines that are not involved in the fire. The water also fails to suppress the toxic gases produced by the burning electrical insulation, wires, and electrical components.
After the fire has been extinguished, a clean-up crew enters the tunnel or conduit to vacuum up the water, particulate ash from the burnt components and other residue created by the fire. This is a costly operation. Finally, after the clean-up crew has completed its job, a crew of electricians enters the tunnel or conduit to replace the electrical transmission lines and other equipment which has been destroyed/damaged with new equipment/components.
Structures are also susceptible to fire, some more than others. Fires can be caused from most any source but one of the most problematic fires is caused when a forest or other vegetation catches fire and a wind accompanies the fire. Such fires are a common occurrence and can easily be started by a lightning strike or the result of a human occurrence. In any event, as the general population continues to build structures in close proximity to large vegetative sources, more and more structures are placed at risk. Unfortunately the number of fire fighters to structures is not proportionate and is getting worse, not better.
Homes abutting a forest or other large vegetation areas are safe as long as the moisture content of the vegetation remains high. Should the vegetation become dry, the vegetation becomes fuel that can support a fire. For instance, while the Florida Everglades may be considered one of the most tropical areas in the United States, during a drought the everglades can catch fire and homes built near the everglades are susceptible to fire damage. Homes in Southern California may abut rugged areas filled with dead brush which can easily support the spread of a fire. Thousands of acres are consumed by fire each year and structure damages are increases as the population grows.
A raging fire can create its own environment with up-drafts and winds that can cause embers to carry to areas otherwise distant from the fire. Southern California is particularly susceptible to embers being carried when the Santa Anna winds occur. The result is that embers can be carried with the wind distributing potentially hazardous fire starters towards homes that would otherwise not be directly next to the forest or brush area. In many instances the homes include wood construction, such as wood shake shingles, which can easily catch fire should hot ember land upon the structure. If the owner of the structure is not in an evacuation zone, the owner may be an able bodied individual who can inhibit spreading of the fire to their structure by keeping high moisture content on the wood.
It is well known that the damage from many natural events can be reduced or eliminated with proper preparation. For instance, the owners of a structure may prepare for a hurricane at the last minute by installing window covers. Those in a fire zone may also be prepared to protect their structure but, unlike a hurricane, the path may be very small and the homeowner may have only a short notice that their structure is in harm's way. The danger of a fire is that while one structure may be located a distance from the fire, it may still catch fire while a structure closer to the fire does not catch fire. For these reasons, most homeowners attempt to protect their structure by using fire resistant products in the construction or repair of their buildings. In many instances the homeowners are not prepared for a fire due to lack of proper tools or funding to protect their structure when an actual fire is approaching. This lack of preparation places adjoining structures at risk.
The most commonly used item in protecting a structure is water. In fact, it is not uncommon to see a homeowner standing on their roof with a garden hose attempting to add moisture to the roof. Unfortunately, the quick evaporation of water due to low humidity and high temperatures can defeat the effort. Water has been known for its fire retardant and extinguishing properties and remains the predominate material used to extinguish or prevent certain types of fires. Water has a high heat capacity and high heat of vaporization, such that when water is sprayed onto a fire, the water that reaches the flames absorbs the heat of the fire and cools the article to below its combustion temperature. Water also deprives the fire of oxygen. Often the heat of the fire turns a portion of water into vapor before it can reach the flames. Since water vapor is heavier than air it displaces the oxygen surrounding the fire, thereby suffocating the fire.
A significant disadvantage often encountered using water to extinguish a fire is that much of it ends up wasted. Water applied directly to the fire mostly evaporates before it can reach the base of the fire, where the combustible fuel for the fire resides. As much as 90 to 95% of the water that does manage to reach the flames simply runs off into the ground. Moreover, considerable effort must be made to continuously soak objects with water near the fire that could ignite as the water evaporates very quickly. In order to maintain protection of the objects from fire the evaporated water must be constantly replaced.
Homeowners are very adept at protecting their homes if they are provided with access to the right materials. Those in a fire zone also attempt to protect their structures but need access to a variety of materials to treat a variety of conditions. For instance, a fire may be accompanied by a high wind that makes standing on a roof with a hose very dangerous. Should the fire turn toward the home the individual could be trapped on the roof. Should the winds pick up, the homeowner could slip on the now slickened roof, or the ladder used to access the roof could fall over.
The most exposed portion of any structure is typically the roof. For this reason a number of prior art devices are directed to the treating of a roof with water should a fire approach. For instance, U.S. Pat. No. 3,583,490 discloses a fire protection system for roofs. The system is for wetting the exterior surface of a building structure to prevent ignition of a fire in the vicinity of the structure. The protection system employs a recirculation water system directing water over both the roof and sidewalls of the structure and an automatic fire detection and control system for activating the water system in response to a fire and terminating operation of the water system when the fire is extinguished. A feature of this system is the collection of water from a rain gutter which is returned to a collection point, such as a swimming pool, for further distribution.